<!DOCTYPE html>
<html lang="en">

<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
  <style>
    * {
      margin: 0;
      padding: 0;
    }

    #box {
      width: 200px;
      height: 300px;
      margin: 200px 200px;
      background: red;
      position: relative;
    }

    .txt {
      width: 150px;
      height: 50px;
      text-align: center;
      line-height: 50px;
      color: #fff;
      font-size: 30px;
      font-weight: 900;
      position: absolute;
      left: 25px;
      top: 50px;
    }

    .hour {
      left: 20px;
    }

    .h_m {
      left: 68px;
    }

    .minute {
      left: 80px;
    }

    .m_s {
      right: 68px;
    }

    .second {
      left: 140px;
    }

    .hour,
    .minute,
    .second {
      position: absolute;
      top: 200px;
      color: #fff;
      font-weight: 800;
      font-size: 20px;
      text-align: center;
      line-height: 40px;
      width: 40px;
      height: 40px;
      background: black;
    }

    .h_m,
    .m_s {
      color: #fff;
      font-size: 20px;
      font-weight: 900;
      position: absolute;
      bottom: 70px;
    }

    .words {
      margin-top: 160px;
      font-size: 18px;
      color: white;
      margin-left: 20px;
      text-align: center;
      position: absolute;
    }
  </style>
</head>

<body>
  <div id="box">
    <div class="txt">京东秒杀</div>
    <div class="words"><strong>16:00</strong> 点场 倒计时</div>
    <div class="hour"></div>
    <!-- 小时与分钟之间的冒号 -->
    <span class="h_m">:</span>
    <div class="minute"></div>
    <!-- 分钟与秒之间的冒号 -->
    <span class="m_s">:</span>
    <div class="second"></div>
  </div>
</body>
<script>
  //1、获取元素
  var hour = document.querySelector(".hour");
  var minute = document.querySelector(".minute");
  var second = document.querySelector(".second");
  var inputTime = +new Date("2023-10-16 18:00:00");//倒计时的结束时间，自己设置时间
  countDown();//先调用一次这个函数 防止第一次刷新页面有空白
  //2、开启定时器
  setInterval(countDown, 1000);//1000毫秒，每一秒钟调用一次函数
  //3、倒计时-时分秒函数
  function countDown() {
    var nowTime = +new Date(); //返回的是当前时间的总的毫秒数
    var times = (inputTime - nowTime) / 1000; // times是剩余时间的总的毫秒数
    var h = parseInt(times / 60 / 60 % 24);
    h = h < 10 ? '0' + h : h;//判断数值小于10的情况 如 0-9改为 00-09
    hour.innerHTML = h;//更改div里面的内容 把h给获取元素hour的内容
    var m = parseInt(times / 60 % 60);
    m = m < 10 ? "0" + m : m;
    minute.innerHTML = m;//同上
    var s = parseInt(times % 60);
    s = s < 10 ? "0" + s : s;
    second.innerHTML = s;//同上
  }
</script>

</html>